In a conventional digital wireless communication equipment of the TDD system, the reception clock is synchronized with the transmission clock of a wireless communication equipment of a base station, one frame is divided into two time slots, and the mobile station and the base station perform the wireless communication in the same frequency. On the other hand, the mobile station uses the frame timing, receives the frame synchronization in synchronization with the time slot of the base station, and by this, can receive only the signal of the terminal of a communication partner.
However, in the mobile station immediately after power-on, or the mobile station immediately after it has been moved from the outside of a wireless communication enable area into the inside of the area, the receive clock is not synchronous with the transmission clock of the wireless communication equipment of the base station, and the frame timing is not also known.
Thus, the mobile station first synchronously receives the communication frequency continuously, and waits for a signal from the base station. The signal from the base station includes a preamble bit repeating a fixed pattern. The mobile station receives the preamble bit asynchronously to reproduce the clock, and synchronizes its own reception clock with this. Further, the signal from the base station contains a synchronous bit, and the base station receives this bit by the clock synchronized with the mobile station.
By this, from a previously determined frame structure and the position of the received synchronous bit, the mobile station grasps the frame synchronous timing of the base station. This is called synchronous establishment.
Conventionally, this type of wireless communication equipment and synchronous establishment method are disclosed in, for example, JP-A-10-84309 (see FIG. 1 and FIG. 3).
However, in the conventional wireless communication equipment, in order that the mobile station side performs the synchronous establishment, it is necessary for the mobile station side to have a demodulation circuit. As a result, the circuit mounting area becomes large, and the mobile station becomes large.